The invention relates to photography and in particular to the development of silver halide photographic elements.
In the development of black-and-white silver halide photographic elements a commonly encountered problem is the accumulation of xe2x80x9csludgexe2x80x9d or xe2x80x9cdirtxe2x80x9d in the developing composition. While the mechanisms whereby such sludge is formed are varied and complex, an important contributing factor is the presence in developing compositions of compounds such as sulfites which dissolve silver halides and form silver complexes. The silver complexes that are extracted from the photographic element into the developing composition are reduced by other components of the developing composition and converted to extremely fine particles of metallic silver which are commonly referred to in the art as xe2x80x9csilver sludge.xe2x80x9d The formation of this silver sludge is a particularly serious problem when the photographic elements are processed in an automatic processing apparatus. Thus, for example, it is common for the sludge to attach to the walls of the developing tank and/or the rollers of an automatic processor and the particles can subsequently transfer to the photographic element. The result can manifest itself as black silver specks or silver stain and, if sufficiently severe, this can render the photographic element useless for its intended purpose. The problem can be alleviated to some extent by frequent cleaning of the processing equipment to remove accumulated silver sludge, but this adds significantly to the effort and expense of the processing operation. The problem of reducing or avoiding the deposition of silver sludge has been a very longstanding problem in the photographic art. A wide variety of compounds has been proposed heretofore as sludge-inhibiting agents. Their effectiveness for this purpose is often insufficient. Moreover, agents used to reduce sludge formation can have unwanted side effects such as suppressing development or adversely affecting the contrast of the photographic element. Sulfites are very commonly used in black-and-white developing compositions where they serve to extend the life of the developing composition by protecting it against aerial oxidation. While they are a major contributor to sludge formation they are not the only one. Other factors contributing to sludge formation include the throughput of sensitized material, the replenishment rate, the time of development, the developing agent and the design of the processing apparatus. Generally speaking, most, if not all, black-and-white developing compositions suffer from the problem of sludge formation, although the degree to which it occurs varies widely depending upon both the components of the developing composition and the composition of the photographic element being processed. U.S. Pat. No. 4,975,354 describes silver halide photographic elements having incorporated therein a hydrazine compound which functions as a nucleator and an amino compound which functions as an incorporated booster. Such elements provide a highly desirable combination of high photographic speed, very high contrast and excellent dot quality, which renders them very useful in the field of graphic arts. Moreover, since they incorporate the booster in the photographic element, rather than using a developing solution containing a booster, they have the further advantage that they are processable in conventional, low cost, rapid-access developers. Other patents describing silver halide photographic elements comprising a hydrazine compound which functions as a nucleator and an amino compound which functions as an incorporated booster include U.S. Pat. No. 4,914,003 and U.S. Pat. No. 5,030,547. Nucleated high-contrast photographic elements of the type described hereinabove are particularly prone to the formation of silver sludge. While the reason for this is not clearly understood, it has been a significant factor hindering the commercial utilization of such otherwise advantageous photographic elements in the field of graphic arts. The present invention is directed toward the objective of providing an improved developing composition, useful with a wide variety of black-and-white silver halide photographic elements, that has less tendency to deposit sludge than developing compositions utilized heretofore. It is a particular objective of the invention to provide an improved process for developing high contrast photographic elements, containing a hydrazine compound which functions as a nucleator and an amino compound which functions as an incorporated booster, utilizing the improved black-and-white developing composition of this invention.
U.S. Pat. No. 4,254,215 describes a process for the prevention of darkening and the formation of a sediment in photographic developer solutions by adding a combination of a mercapto compound and a Bunte salt to the developer solution. The mercapto compound may be a thiol of the formula HSxe2x80x94Dxe2x80x94(W)n where D is a substituted or unsubstituted aliphatic, araliphatic, cycloaliphatic, aromatic or heterocyclic radical and W may be a group of the typexe2x80x94CONH2.
Problem to be solved by the Invention
It is an aim of the invention to provide an alternative developer composition in which silver sludge formation is reduced.
It is an aim of the invention to provide a developer composition containing a silver antisludging agent in which the rate of loss of antisludging activity on dilution is decreased.
It is an aim of the invention to provide a developer composition containing a silver antisludging agent in which the loss of antisludging activity on prolonged keeping is diminished.
In one aspect the invention provides a photographic developer composition for use in the development of a black and white silver halide photographic element said composition comprising at least one developing agent and, in an amount sufficient to inhibit sludge deposition, one or more compounds selected from compounds having the formula
Xxe2x80x94R1xe2x80x94CONHxe2x80x94Axe2x80x94Sxe2x80x94Sxe2x80x94Bxe2x80x94NHCOxe2x80x94R2xe2x80x94Yxe2x80x83xe2x80x83(I) 
wherein
A and B are each independently a substituted or unsubstituted aliphatic, alicyclic, aromatic or heterocyclic group;
R1 and R2 are each independently a substituted or unsubstituted aliphatic, alicyclic, aromatic or heterocyclic group;
X and Y are each independently a solubilising group;
and compounds having the formula
Xxe2x80x94R1xe2x80x94CONHxe2x80x94Axe2x80x94Sxe2x80x94Mxe2x80x83xe2x80x83(II) 
wherein A, R1 and X are as defined above, and
M is either a hydrogen atom or a cationic species if the sulfur atom is in its ionised form.
In another aspect, the invention provides a method of forming a photographic image in a black and white silver halide photographic element which comprises imagewise exposing the photographic element and developing the exposed element with a developing composition comprising at least one developing agent and, in an amount sufficient to inhibit sludge deposition, a compound having the formula (I) and/or (II) as defined above.
In another aspect, the invention provides a black and white silver halide photographic element comprising a support having thereon at least one light-sensitive silver halide emulsion layer said element comprising, in an amount sufficient to inhibit sludge deposition during development, a compound having the formula (I) and/or (II) as defined above.
Advantageous Effect of the Invention
Use of the developer composition of the invention reduces sludge formation.
The antisludging activity of the developer composition diminishes only gradually on dilution.
The antisludging activity loss of the developer composition on prolonged keeping is diminished.